A fantasy novel for young and old in which the lives of the Selby Children are threatened with disruption as their parents leave them in the care of the fearsome Gerda in a mansion in Notting Hill. The house's previous owner mysteriously vanished and the children discover that he was a great traveler on an extra-dimensional magical railway. Together they travel the magic railway and the youngest, Rosy, finds herself in the midst of a life and death struggle involving the Grail and the restoration of order and balance to the world.